Category Archives: The Earth

What Do Plants Need to Live?

Cows by hencio

People like you and I need a few things to live — we need healthy food, we need water, and we need air. Plants, though, are a little different than you and me. They need food and water, but they also need sunlight to live. Plants use sunlight as a way to make energy to grow.

Plants and animals, including people like you and me, breathe in air. But plants use a different part of the air than you or I do. We breathe in a part of the air called oxygen. We use the oxygen that we breathe in the air to feed the blood in our bodies. Plants use a different part of the air, a gas called carbon dioxide. We breathe in oxygen and breathe out carbon dioxide. Plants do just the opposite — plants breathe in carbon dioxide and breathe out oxygen. So the oxgyen you’re breathing now probably came from a plant. Thanks, plants!

Plants also get food from the soil. To live, they need a certain chemical that you can find in the soil. This chemical is called nitrogen. You have nitrogen in your body, too, but your body can’t use it. So when you get nitrogen in your body, your body gets rid of it. How does it do this? It leaves your body through pee and poo. All the stuff in pee and poo is stuff that your body can’t use. That’s why pee and poo is sometimes called “waste” — because it’s something leftover that you can’t use.

But because pee and poo are full of nitrogen, plants love it! If you’re a tree and a dog pees on you, are you happy or sad? You’re happy, because that pee is full of nitrogen that you can use to eat. The same is true with poo. In fact, farmers take poo from their cows and spread it across their fields to make the plants in their fields grow better. This is called “fertilization” — the farmer is using cow poo to make it easier for plants to grow in the field.

Why Are Humans Animals?

Helena and Putto by jeffreymcmanus

Are humans animals? We don’t usually think of ourselves as being similar to dogs, cats or frogs, but to scientists, in many ways we are.

Scientists mostly divide the world of living things into animals and plants. If something gets its energy from sunlight and doesn’t move around on its own, a scientist will usually call that creature a plant. Grass, moss, pumpkins and apple trees are all examples of plants.

If a creature gets its energy from eating other things and it can move around on its own, then scientists call it an animal. Dogs, cats, frogs, fish, dinosaurs, and humans are all examples of animals.

Scientists have names for different kinds of animals depending on which kind of food they like to eat. An animal that eats mostly plants is called an herbivore. Horses and sheep are herbivores. Animals that eat mostly meat are called carnivores. Lions and tigers are carnivores. People are omnivores — we can eat both meat and plants (although some people choose not to). Dogs and pigs, as well as some birds and some fish, are also omnivores.

What Is Matter?

Your body, your house, your dog, the Earth: all these things are made of matter. Matter is the name that scientists give to all of the substances in the universe.

Is water a kind of matter? Yes, water is a kind of matter called a liquid. Other kinds of liquid include milk and the gasoline we pump into our cars. Water is by far the most common form of liquid on Earth, though — most of the Earth’s surface is covered by water.

Wave your hand through the air. You can feel the air wooshing past your hand. Is the air made of matter? Yes, air is a kind of matter called a gas.  Other kinds of gasses include carbon dioxide (which plants breathe) and helium (which is used to make toy balloons float).

Most of the things you can see or touch are made of matter. Even things you can’t see (like the air) are made of matter. Are there things in this world that aren’t made of matter? Yes: some things are made of energy, which is different than matter. There are lots of ways to see energy in the world. Sunlight is a kind of energy. When a bolt of lightning hits the Earth during a storm, that’s energy too.

How Do Trees and Plants Help Us?

Tree by nickatkins

When you take in a breath, what happens? If you take a big breath, you can feel air going into your body through your mouth. But why do we breathe? We breathe because our bodies need something in the air called oxygen. Oxygen is like food for our blood. You can’t see oxygen, but it’s there in the air, and people and animals need it to live.

Your body changes oxygen into a different gas called carbon dioxide. Carbon dioxide is what comes out of your body when you breathe out. You breathe in oxygen, and you breathe out carbon dioxide.

Trees and plants don’t breathe oxygen as we do. They take in carbon dioxide and they put out oxygen — just the opposite of people and animals. So having lots of plants around is good for people and animals — plants and trees make the oxygen that we need to breathe.

What Is A Volcano?

Volcano by kahunapulej

A volcano is a special kind of mountain. Volcanos are special because they can erupt. When a volcano erupts, it can sent hot lava, steam, ash, and rocks into the air.

The heat from a volcano comes from deep within the earth. Many miles underground, the earth is hot. Rocks beneath the earth are so hot they turn into a liquid called lava. When a volcano erupts, the steam and ash is caused by lava that is forcing its way toward the surface of the earth.

We don’t find volcanos in every part of the world. In the United States, most of the volcanos are in Hawaii and Alaska. There are quite a few volcanos in Asian countries such as Japan. The largest active volcano in Europe is called Mount Etna, in Italy.

You don’t have to be worried about being hurt by a volcano. Volcanos erupt very rarely, and most volcanos don’t hurt anybody when they erupt.

Why Do Seasons Happen?

Winter, by iguanajo

You’ve probably noticed that it gets warmer in summer and colder in the winter. This change happens every year. It happens because the earth tilts back and forth as it goes around the sun. During the summer, the earth tilts toward the sun, which makes half of the earth hotter — this is what we call summer. During the other half of the year, the earth tilts away from the sun, which makes that half of the earth cooler. We call this winter.

Did you know that different parts of the world have winter and summer at different times of the year? In the northern half of the world (such as North America and Europe), winter happens during the months of December, January and February. In the southern half of the world (such as South America and Australia), winter happens during the months of June, July and August. Winter happens at different times because the top and bottom halves of the earth tilt away from the sun at different times of the year.